As is known in the art, electric cars and hybrid cars are equipped with an electric power source for an electric motor, which serves as a drive source. The electric power source is a storage battery (a rechargeable battery). One of systems for charging such a storage battery includes a non-contact charging system that supplies electric power from a power supplying apparatus to the storage battery in a noncontact manner without using a power supply cable. For example, the non-contact charging system includes a power transmitter coil included in the power supplying apparatus previously embedded in the ground surface and a power receiver coil mounted on the lower section of the body of a car to be charged. When the power receiver coil is located to face the power transmitter coil, electric power is transmitted by mutual induction or resonance through electromagnetic connection from the power transmitter coil to the power receiver coil.
A charging system may charge multiple cars at the same time by providing multiple power transmitter coils. In this case, when multiple cars are located with respect to the multiple power transmitter coils at the same time, the power supplying apparatus may possibly fail to determine which of the cars corresponds to each power transmitter coil, that is, the power supplying apparatus may possibly fail to perform the pair process. Patent Document 1, or International Publication WO2012/111127, discloses an example of techniques for pairing the power transmitter coils with cars even if multiple cars are located with respect to the multiple power transmitter coils at the same time.
Patent Document 1, or International. Publication WO2012/111127, discloses multiple charging devices, each of which includes a power transmitter coil for transmitting electric power to a car, and a charge control device, which transmits a first signal to the charging devices. One of the charging devices outputs, from the power transmitter coil, a second signal designated by the first signal. The car transmits a third signal corresponding to the second signal through wireless communication. The charge control device includes output means for transmitting the first signal, detecting means for detecting the third signal, and recognition means. The recognition means associates, or pairs, one of the charging devices with one of the cars based on the transmitted first signal and the detected third signal.